<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let num1 = 1,
            num2=2.1;
    console.log(typeof num1);
    console.log(typeof num2);
    console.log(num2 + 0.2);
    let str1 = '亚';
    let str2 = '索';
    console.log(str1 + str2);
    console.log(`${str1}${str2}`)
    console.log('永恩' + 1)

    let a; // JS是弱类型语言，未赋值情况下编译器不能确定其内存
    console.log(typeof a); //undefined 值的类型未确定
    a = 1;
    console.log(typeof a);
    let b = null;
    let c = undefined;
    let d = true;
    //对象字面量
    let mm = {
        name:'喵喵',
        hometown:'萍乡',
        isSignle:true
    }
    console.log(typeof mm)
    </script>
</body>
</html>